Ceramic- and glass ceramic materials are used as dental materials due to their mechanical properties and aesthetics. The all-ceramic materials, such as zirconia and alumina, have the advantage of high mechanical properties, but are opaque and thus less aesthetically pleasing and more difficult to adapt to the colour of the surrounding teeth than glass ceramic materials such as lithium disilicates (Li2Si2O5), which are translucent. However, the glass ceramic materials generally have a fracture toughness and flexural strength considerably lower than the all-ceramic materials do. A translucent material with improved mechanical properties is desirable for dental restoration applications.
Lithium disilicate glass ceramic materials have appealing optical properties in the finally prepared restoration, such as translucence and shade, which imitate the appearance of the natural teeth. They further show high strength and chemical durability so that they can take over the function of the natural tooth material and maintain these properties over a sufficient period of time while being permanently in contact with fluids in the oral cavity. It is also desirable to machine them in an easy manner into the desired shape without undue wear of the tools and within short times.
US2009/0042714 discloses lithium silicate materials for use in dental products.
There is an increasing demand for new methods of producing crack-free samples with desirable mechanical properties and attractive appearance resembling natural teeth, having large sizes suitable for large dental works such as bridges, for example samples larger than 1 cm3.